The Church of South India was inaugurated in 1947, after thirty years of union negotiations between the South India United Church - the combined body of Presbyterians and Congregationalists - the Anglican dioceses in South India and the South Indian districts of the Methodist Church. Out of the 22 dioceses of the CSI one is in Jaffna, Sri Lanka. The basis of the constitution is the Lambeth Quadrilateral, the historical episcopate being accepted in a constitutional form. From the beginning all ordinations have been by bishops. The mission statement of the CSI is "The Church of South India affirms that the church is the servant of God to carry on the mission rooted in Jesus Christ and based on the scriptures. The church through her mission, expresses solidarity with the broken communities for a new hope to face the challenges of life. The cross continues to be the sign of hope for the witnessing church, which strives towards unity, peace and reconciliation as a vibrant channel of God".

Resolutions of the Lambeth Conference of 1968 and the Anglican Consultative Council of 1971 advised Anglican churches and provinces to re-examine their relation to the CSI with a view to entering into full communion with that church. More recently the CSI, the Church of North India and the Mar Thoma Syrian Church of Malabar have formed the Communion of Churches in India (2003), as a further step towards unity.

Primary concerns of the CSI are evangelism and social justice. Major programmes and activities of the CSI are: evangelism, stewardship, healing and educational ministries, technical and vocational training, rural and urban development, Christian nurture of the congregation, theological education and training of pastors.